Sear locking device for automatic firearms



Dec. 20, 1949 A, P, TABER sEAR LOCKING DEVICE FOR AUTOMATIC FIREARMS Filed July ll, 1947 'l Al damp.. Til: E I\ @im @ZQMf/MW www Patented Dec. 20, 1949 Uir STTES PATENT OFF SEAB LOCKING DEVICE FOR AUTOMATIC FIREARM (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 12 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of royalty thereon.

This invention relates to a device for locking the sear of automatic rearms in the cocked position to prevent premature release of the percussion member during the counter-recoil travel of the bolt member of the rearm.

In automatic rearms, particularly machine guns, and more especially machine guns of the type shown in the U. S. patent to Browning 1,628 226, premature release of the firing pin by the sear has been a constant source of annoyance. Various means and exhaustive investigation have been resorted to in an attempt to overcome this deficiency but so far have not met with any great measure oi success.

Failure of the sear to maintain engagement with the ring pin, or other percussion element that may be engaged by the sear upon cocking of such members, will result in either premature discharge of the cartridge with corresponding disastrous results, or failure to ignite the cartridge through lack of a proper blow on the primer in the locked position of the firearm bolt. The latter malfunction is the type most usually experienced with the Browning machine gun. This obviously results in a stoppage of the gun requiring manual recharging thereof in order to again place the iirearm in functioning order.

Accordingly, it is an object of this invention to provide a locking device for the sear mechanism oi an automatic firearm to insure that the sear will maintain engagement of the percussion element in the cooked position until the bolt member is locked in battery position.

Another obiect of this invention is to provide a locking device for the sear of an automatic rea-rm to lock such sear in the cocked position during the counter-recoil movement of a reciprocating breech member wherein an element of the reciprocating breech member is utilized to actuate such sear locking device.

A particular object of this invention is to provide a positive sear locking device for an automatic machine gun of the Browning type.

The specific nature of this invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. l is a perspective view of the elements of this invention removed from the firearm bolt and arranged in cooperative relationship and showing the sear locking lever engaging the sear in locked relationship.

Fig. 2 is a rear end view of the rearm bolt incorporating the elements of this invention.

Fig. 3 is a sectional View taken along the line 3-3 of Fig. 2.

Fig. 4 is a sectional view taken along the line 4--4 of Fig. 2.

Fig. 5 is a detail view showing the longitudinal slot utilized to accommodate the sear locking lever and its position with respect to the various other slots in the bolt.

Fig. 6 is an enlarged detail view showing the detent recesses provided on the underside of the sear locking lever.

The sear locking device of this invention comprises mainly a sear locking lever pivotally mounted on a firearm bolt by a vertically disposed pin. Such pin is secured against displacement by a transversely disposed cooking lever pin. The sear locking lever is provided with a cam cut on one side thereof which is contacted by a cooking lever of the bolt. In the cocked position of the sear, the sear locking lever engages a transverse notch in the sear to hold such sear locked in the cocked position. Reciprocation of the bolt pivots the cocking lever and such cocking lever, being in engagement with the cam provided on the sear locking lever, effects sideways pivotal movement of the locking lever so that the end in engagement with the notch provided on the sear is pivoted out of such notch, whereupon the usual sear release means is operative to eiect release of the sear. Detent means is provided to yieldingly hold the sear locking lever in either the locked or unlocked position.

There is shown in Figs. 3 and 4, a rearm bolt I0 embodying the sear locking device. Such locking device comprises a sear locking lever II, a pin I2 for pivotally mounting locking lever II to the bolt, and a detent I3. Bolt IIJ is the well known Browning machine gun bolt and is identical to that used in present day Browning machine guns with the exception of minor modications thereto in order to adapt the sear locking device of this invention to such bolt. These modifications consist largely of adding a sear locking lever slot I4, as shown, to accommodate the sear locking lever II and the provision of two holes to accommodate pin I2 and detent I3 as will be described.

Sear locking lever slot I4 is formed within a vertically disposed slot I6 provided in the rear end of bolt I0. VSlot Ill is longitudinally disposed in vertical slot I6 on the right side, somewhat below the top surface of bolt I0 as shown in Fig. 3. At approximately the center portion of slot I4 there is provided a vertically disposed hole I1. Such hole intersects and communicates with a transverse cooking lever pin ho1eI8. Hole I'I is provided at the top thereof with a counterbore I9. Somewhat forward of hole I'I there is provided another vertically disposed hole having a counterborevZI. Hlef is provided to-receive detent I 31":as "will-- bei later described'- Sear locking lever I I is pivotally mounted within slot I4 by pin I2. A transverse hole 22 in lever;

II accommodates pin I2 to `secure suchY lever within slot I4. Lever II is essentially an flat member and is provided with a reduced width,

rear end portion 23 which is utilized=to-engagea sear 24 as will be later described. A cam surface 25 is provided on lever II which is'disposed adjacent a cooking lever 26. Cooking lever 261s pivotally mounted within vertically disposed slot I6 by a pin 2'I supported in= the -transversehole I8 in bolt It. Pin 21 and cocking lever '26 are conventional components of the Browning machine gunfbolt and needfhotvbrfurther described,

cated asshown at 28 'whichf accommodates an annular groove 29 provided near the lower end of pin "I 2 ftherebyvseeuring such` pin: withinrhole Il. It, should be mentioned that pin I2 `is provided with-fan integralheadvv 3U which' nts lwithin coun.- terloore-'IfA conical point 32 thereon and a stemportion 33."

Holei 20-iaccommodates-stemportion 33 of detent I Sand a 'spring' V'im isprovided about steml v33 'fand is contained within counterborew-ZI `'of hole 2Q;

Conical ,end-'32' V`of detent I3 is' arranged to engage one :of two vconic'ally-shapedfrecesses --35 -providedv on 'the underside-fof lockinglever I I Se'ar 2d isf-also'-v oficonventional construction with l.theexceptionof'atransverse notch 3e provdednearthe upper right-handedgethereof as shown'inFig-:Q- Such-Sear is mounted within the r usual opposed vertically disposed groovesz rprovidedV near f the lrearfendof *the bolt Vonv opposite sides lofi'slot 'IS' In'onepositionof cooking lever 26"," as will'be iaterdescribed, end23 "or lever II engages V'ariotch' 36 ofsear 2d.l A longitudinally disposed jhole" "31 provided in bolt I l'accommoe dates 1ai'lring pin3 8 Firing 'f-pin- 38 .isi alsof of conventionalV construction and need not bevi-further rdescribed except'to -mentionthat a hook-por;l tion eiprovided onfthe vextreme rear end-of fir` ing; pin" 33 engages arsear -notch lid-provided Vin Y sear 241i In Fig.V l thesear locking lever I I isshown locking. the sear 24.' Insuch'position, end 23 'of lever iI engages "notch ifof sear 24.-" The Yposition of 'cooking lever Zinsuchrlg'ure` -is that 'obtained when -the boltislatthe eXtreme-recoiled posiidolo...V Cockingof "thexringjpin'has then been eiectedrand sean-26' is' engaging iiring-pint.

vCooking klever 26; inthis position engages `the forward portion'of ica-rn surface 25. As the bolt' goes into batterypositionjin thfe'rearm (not shownl, cockingleverjZS islrotatedin a counter-K- clock'wise .direction and such levercontacts the:

rearward 'portio'ntof camrsurface 25"thereby rotatinglever'II about'pin'dZ so that end 23A is'l brought out of engagement with notch 3631 When 'a downward'forcehas beenexerted on sear 24 against the biasof a sear spring 4I, hook' portion 39, of nring pin 38 will be disengaged from seannotch ,thus permitting ring pin :it to go forwardly under the bias of the ring pin spring (notshownito, discharge. a cartridge. Detent I3 meanwhile engages the corresponding conical recess; 351:0 yieldinglyseoure lever. II in the sear.

lockingBorunlockng-cpositona desiredto--point'outthat the device herein described is of simple and sturdy construction requiring butrslight modification of existing parts of the firearm and the addition of but few additional parts. Further, the device herein disclosed is adaptable to a firearm bolt constructed and arranged to fire from either the right or left side by simple rearrangement of the sear locking lever I claim: 1.1 In i an automatic :rearmthaving rafreciproeating breecha mem-ber; ai ringz-v pin; slidably mounted rin :the fbreech.3v member,`A a cooking lever:-` rotatably mounted on the breecli'memberfandr, arranged to cock thelilringapinonf'thef recoil movement z of :therfbreech :member-,1v andI a sear arranged to :holdthe firing .;pin; in: 'a- Ycocked: poe

sition; ,the improvement comprising; a sear lock-z ing lever, and cam'fmeans ont said `lockingfleverl;

engageable '-.byfthe cooking:leverzto-.lock fthe-.scar

in-A :the @cocked :position duringethe -recoilrn1ove-s ment. or'the rbreechrmember;V

2; Iman-:automatic rearmfhavingg-areciproe 1 eating breechV member; ,a ringf; ping. sl-idably mounted; inthebreech member; a. cooking leverf; rotatably -mounted i: onz'the .breechlrmember .andai arranged t to frcockz .the :ringj pin :on the; recoil:

movement of the breech member,f.;anda .seararranged to Vsholdiz-the fring pinyin a f cocked :posi:v

tion', the i improvement` comprising,I afsear. :lock'ring lever,:cam:=mea=ns :on said -lockingiqlever-forflockingfthek searxin 'the cocked 'position-during the recoil movement `of-.the lbreech xmember;` said.` cam means beingengageable by the i::ockingfleverzv during rotation of; the cooking lever in-'one .directionto lo'ckthe` searfincocked relationship with i the firing .jpinandpsaid :cam-means engageable.:-. by the cooking;lever"duringrotation-offthe cocl ing lever inzthe other direction to unldckthesear' so that the'.sea1 may-,be disengaged from :their ring pin.

3; InA combinationrwith an` automatic frearm having Va 'reciprocating/bolt including airing;` pin, sear; andta rotatableY cooking leverga `sear,A locking device comprising a isear i lookingv leverz-A pivotally mountedin'ithefboltand cam means on said sear locking lever engageableby theacocking said locking leverizinto'locking'engagement'"with the sear when the -ring piniis held in the .cockedr position `by the sea-r,-` saidf cam'flmea'ns son vvsaidr" locking lever being A#engagea-ble by thecooking lever 'on-"the counter-recoil strokefof the bolt'toY disengage said lockingflever ffrom; the. searfby."

the time the boltreaches 4battery.'positiomwheref upon the firing pinimay -b'eV released fromengage-1- ment with the scar:

4. In combinationiwith anrautomatioirearm having a reciprocating fboltincluding a ring pin; sear; and a rotatable 'cooking lever, a searrlocking device comprising ja -sear docking lever pivotally? i" mounted in the bolt, cam means on saidxsear.:

locking leverengageable by-'the Vcooking :lever on the recoil stroke-of the-bolt tofpiv'ot said'lockingfr` lever into locking 'engagement withth'e sear when: the ring pin is heldvinthe cockedposition by ythe sear, said cam means on said locking lever being engageable by the cocking lever on the counterrecoil stroke of the bolt to disengage said locking lever from the sear by the time the bolt reaches battery position whereupon the ring pin may be released from engagement with the sear, and detent means arranged to yieldingly hold said locking lever in either the sear engaging position or disengaged position.

5. In an automatic firearm, a reciprocating bolt, a sear looking device comprising in combination, a firing pin slidably mounted in the bolt, a sear slidably mounted in the bolt and arranged to hold said ring pin in the cocked position, said Sear having a notch therein, a cooking lever in the bolt arranged to cock said ring pin on the recoil stroke of the bolt, a sear locking lever mounted in the bolt for pivotal movement in a horizontal plane, and cam means on said locking lever engageable by said cooking lever on the recoil stroke of the bolt to pivot said locking lever into said notch on said sear to lock said scar against premature release, said cam means on said locking lever being engageable by said cooking lever on the counter-recoil stroke of the bolt to unlock said sear as the bolt goes into battery position.

6. In an automatic firearm, a reciprocating bolt, a sear locking device comprising in combination, a iring pin slidably mounted for longitudinal movement in the bolt, a sear mounted in the rear of the bolt for vertical movement and arranged to hold said firing pin in the cocked position, said sear having a notch therein, a vertical pin mounted forwardly of said sear, a transverse pin adapted to secure said vertical pin in the bolt, a cooking lever mounted on said transverse pin for pivotal movement in a vertical plane in the bolt, said cooking lever being arranged to cock said firing pin on the recoil stroke of the bolt, a sear locking lever mounted in the bolt on said vertical pin for pivotal movement in a horizontal plane, cam means on said locking lever engageable by said cooking lever on the recoil stroke of the bolt to pivot said locking lever into said notch on said sear to lock said sear against premature release, said cam means on said locking lever being engageable by said cocking lever on the counter-recoil stroke of the bolt to unlock said sear as the bolt goes into battery position, whereupon release of said firing pin by said sear may be effected, and detent means arranged to yieldingly hold said locking lever in either the sear engaging position or disengaged position.

'7. In an automatic rearm having a reciprocating breech member, a ring pin slidably mounted in the breech member, a cooking lever rotatably mounted on the breech member and arranged to cock the ring pin on the recoil movement of the breech member, and a sear arranged to hold the firing pin in a cocked position, the improvement comprising, a lever for locking the sear in the cocked position during the recoil movement of the gun.

8. In an automatic firearm, the combination of a reciprocating breech member, a ring pin slidably mounted in the breech member, a cocking lever rotatably mounted on the breech member and arranged to cock the firing pin on the recoil movement of the breech member, a Sear arranged to hold the firing pin in a cocked position, and a lever for locking the sear in the cocked position during the recoil movement of the gun,

9. In an automatic rearm, the combination of a reciprocating breech member, a firing pin slidably mounted in the breech member, a oooking 1rever rotatably mounted on the breech member and arranged to cock the firing pin on the recoil movement of the breech member, a scar arranged to hold the iiring pin in a :cocked position, a scar locking lever, and cam means on said locking lever engageable by the cooking lever to lock the sear in the cocked position during the recoil movement of the breech member.

3.6. In an automatic firearm having a reciprocating breech member, a firing pin slidably mounted in the breech member, a cooking lever rotatably mounted on the breech `member' and arranged to cock the ring pin on the recoil movement of the breech member, and a sear arranged to hold the ring pin in a cocked position, the improvement comprising, a lever for locking the scar in the cocked position during the recoil movement of the breech member, said lever being engageable by the cooking lever during rotation of the cooking lever in one direction to look the sear in cocked relationship with the firing pin, and said lever engageable by the cocking lever olurin 7 rotation of the cooking lever in the other direction to unlock the sear so that the sear may be disengaged from the ring pin.

11. In an automatic rearm, the combination of a reciprocating breech member, a firing pin slidably mounted in the breech member, a cocking lever rotatably mounted on the breech member and arranged to cock the ring pin on the recoil movement of the breech member, a Sear arranged to hold the ring pin in a cooked position, a lever for locking the sear in the cocked position during the recoil movement of the breech member, said lever being engageable by the cocking lever during rotation of the cooking lever in one direction to lock the sear in cocked relationship with the ring pin, and said lever engageable by the cooking lever during rotation of the cooking lever in the other direction to unlock the sear so that the sear may be disengaged from the firing pin.

12. In an automatic iirearm, the combination of a reciprocating breech member, a ring pin slidably mounted in the breech member, a cocking lever rotatably mounted on the breech member and arranged to cock the ring pin on the recoil movement of the breech member, a sear arranged to hold the ring pin in a cocked position, a sear locking lever, cam means on said locking lever for looking the Sear in the cooked position during the recoil movement of the breech member, said cam means being operable by the cooking lever during rotation of the cooking lever in one direction to lock the sear in cocked relationship with the ring pin, and said cam means operable by the cooking lever during rotation of the cooking lever in the other direction to unlock the sear so that the sear may be disengaged from the ring pin.

- ALDEN P. TABER.

REFERENCES CITED UNITED STATES PATENTS Name Date Williams K Y Jan. 14, 1936 Number 

